BOTANY Higher Secondary Second Year - Textbooks Online

Stopping codons UAA, UAG and UGA signal the completion of
polypeptide chain. Then, the polypeptide chain is released from the
ribosomes with the help of release factors. The proteins become biologically
active when they are folded to attain three-dimensional configuration.
This is achieved by the attachment of phosphate or any prosthetic group
to the protein.
Self evaluation
I . Choose and write the correct options.
1. RNA is universally present in all organisms except in _____
a. TMV
b. bacteria
c. algae
d. DNA viruses
2. mRNA is about _____ of the RNA content of the cell
a. 10 - 20%
b. 5 - 10%
c. 3 - 5%
d. 20 - 30%
3. In bacterial cell, there are more than _____ tRNAs
a. 200
b. 70
c. 300
d. 400
II. Answer the following questions in two or three sentences.
4. What are isoacceptor tRNAs?
5. What are the four arms found in the clover leaf structure of tRNA?
III. Answer the following questions in about 100 words.
6. Write short notes on the structure of t-RNA.
7. Write the differences between DNA and RNA.
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